Tens of millions of Congolese went to the polls last Monday. It was an emotional day: women with infants strapped to their back waited for hours in the sun, while elsewhere old men hobbled through knee-deep water to cast their ballots. And yet, as the country heads towards a post-election crisis, western diplomats seem ready to see the voters' verdict sacrificed for a misguided notion of stability.

These elections, the second since the end of a bloody civil war, have been mired in controversy for the past year. In January, President Joseph Kabila's party orchestrated a change in the constitution, getting rid of a runoff round of polls for the presidency. This effectively pitted opposition candidates against each other, improving Kabila's chances. The election law was also changed, allowing the ruling coalition to appoint the head of the election commission. Nonetheless, the incumbent has faced stiff competition, especially from firebrand opposition leader Etienne Tshisekedi, who has been able to attract crowds of over 100,000 people. There has been no reliable polling, but preliminary results from voting stations suggest that the race is tight, meaning even minor rigging could be a game-changer.

Then, election day came with a crescendo of controversy. While most of the country voted peacefully, there were hundreds of incidents small and large. In the central Kasai provinces, dozens of polling stations had to close or were burned down by mobs following allegations of fraud. In the east, soldiers in Masisi territory forced voters in dozens of villages to vote for their candidate, in one case tying up voters and taking their ID cards to vote for them. In the western city of Mbandaka, the provincial governor chased opposition witnesses out of his polling station and then spent almost an hour inside before leaving.

Election results are now being compiled, with official tallies showing Kabila leading by a hefty margin. But these figures are again hotly contested, not least because the election commission has not disaggregated the results by polling station, so they can be crosschecked with those of independent observers. Opposition parties, which had officials in most polling stations countrywide, say they have proof the tallies are false. This is the basic bind the country is in: with the credibility of the election commission tarnished, neither of the main contenders will accept defeat. Tshisekedi had declared himself the winner, while Kabila's campaign has said it can't lose.

The sad truth is that it is no longer a question of whether there will be a crisis tomorrow, when official results are supposed to be announced; the question is how bad it will be. Kinshasa is simmering with rumours and anger, while police and presidential guards have been deployed in force throughout town. If Kabila is announced the winner, there will be urban unrest. If Tshisekedi perseveres, army officers in various parts of the country have threatened violence.

In the face of this predicament, the reaction of senior diplomats has been half-hearted. In a closed-door meeting of the UN security council on Friday, some European countries voiced concern at the irregularities, but the body was too divided to take a strong stance. Only one ambassador took part in the meeting; others were too busy working on Syria and Egypt. According to sources present at the meeting, the council thinks it will be difficult to know how much fraud took place and whether it affected the outcome. The priority is to prevent the UN from becoming an arbiter and to ensure stability. The fact that ambassadors find Tshisekedi an unsavoury leader does not help matters.

Their analysis and priorities are ill-founded. The Democratic Republic of the Congo has suffered from violence for the past 15 years, often due to unaccountable leadership. Looking the other way as polls are rigged will hardly make the country more stable. It is also not true that we may never get to the bottom of electoral fraud. There are around 40,000 Congolese observers from churches and civil society monitoring the polls, alongside several hundred foreigners. The election commission must urgently publish poll results in a disaggregated form, so observers can verify them. Polls should then be held again in the many places where they were cancelled, and allegations of fraud jointly investigated with international observers.

We are entering a critical period in Congolese history. Foreign countries, which provide over $3bn in aid a year to Congo, have a heavy responsibility to allow the Congolese decide their own fate. They should not shirk it.